Technical Field
The present invention relates to a method for distributing powder in additive manufacturing of a three dimensional article.
Description of Related Art
Freeform fabrication or additive manufacturing is a method for forming three-dimensional articles through successive fusion of chosen parts of powder layers applied to a worktable.
An additive manufacturing apparatus may comprise a work table on which the three-dimensional article is to be formed, a powder dispenser or powder distributor, arranged to lay down a thin layer of powder on the work table for the formation of a powder bed, a high energy beam for delivering energy to the powder whereby fusion of the powder takes place, elements for control of the energy given off by the energy beam over the powder bed for the formation of a cross section of the three-dimensional article through fusion of parts of the powder bed, and a controlling computer, in which information is stored concerning consecutive cross sections of the three-dimensional article. A three-dimensional article is formed through consecutive fusions of consecutively formed cross sections of powder layers, successively laid down by the powder dispenser.
In additive manufacturing it is important to control the powder distribution. It is desirably to distribute a predefined amount of powder over a predetermined area. This requires a well-defined method and apparatus for repeatedly providing a predetermined thickness of powder on the work table. A not entirely insignificant problem is that the powder layer may now and then be provided with a non-homogenous thickness and/or not sufficient powder density. Such irregularities may affect the quality of the final three-dimensional article in the form of poor material properties, porosities, process instability, poor surface quality and/or dimensional changes and/or surface distortions.